/*
 * Copyright (C) 2011, 2012 Apple Inc. All Rights Reserved.
 * Copyright (C) 2014 Raspberry Pi Foundation. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "MemoryPressureHandler.h"

#if OS(LINUX)

#include <errno.h>
#include <fcntl.h>
#include <malloc.h>
#include <sys/eventfd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <wtf/CurrentTime.h>
#include <wtf/MainThread.h>
#include <platform/Logging.h>
//#include <wtf/MemoryFootprint.h>
//#include <wtf/linux/CurrentProcessMemoryStatus.h>
#include <wtf/text/WTFString.h>
#define LOG_CHANNEL_PREFIX Log

namespace WebCore {

// Disable memory event reception for a minimum of s_minimumHoldOffTime
// seconds after receiving an event. Don't let events fire any sooner than
// s_holdOffMultiplier times the last cleanup processing time. Effectively
// this is 1 / s_holdOffMultiplier percent of the time.
// If after releasing the memory we don't free at least s_minimumBytesFreedToUseMinimumHoldOffTime,
// we wait longer to try again (s_maximumHoldOffTime).
// These value seems reasonable and testing verifies that it throttles frequent
// low memory events, greatly reducing CPU usage.
static const unsigned s_minimumHoldOffTime = 5;
static const unsigned s_maximumHoldOffTime = 30;
static const size_t s_minimumBytesFreedToUseMinimumHoldOffTime = 1 * MB;
static const unsigned s_holdOffMultiplier = 20;

void MemoryPressureHandler::install(){
    printf("MemoryPressureHandler::install installed=%d actived=%d\r\n",m_installed,m_holdOffTimer.isActive());
    if (m_installed || m_holdOffTimer.isActive())
        return;

    if (ReliefLogger::loggingEnabled() && isUnderMemoryPressure())
        LOG(MemoryPressure, "System is no longer under memory pressure.");
    setUnderMemoryPressure(false);
    m_installed = true;
}

void MemoryPressureHandler::uninstall(){
    if (!m_installed)
        return;

    m_holdOffTimer.stop();
    m_installed = false;
}

void MemoryPressureHandler::holdOffTimerFired(){
    LOG(MemoryPressure,"MemoryPressureHandler::holdOffTimerFired\r\n");
    install();
}

void MemoryPressureHandler::holdOff(unsigned seconds){
    m_holdOffTimer.startOneShot(seconds);
}

static void currentProcessMemoryStatus(ProcessMemoryStatus& memoryStatus){
    FILE* file = fopen("/proc/self/statm", "r");
    if (!file)
        return;

    char buffer[128];
    char* line = fgets(buffer, 128, file);
    fclose(file);
    if (!line)
        return;

    size_t pageSize = sysconf(_SC_PAGESIZE)/1024;//WTF::pageSize();
    char* end = nullptr;
    unsigned long long intValue = strtoull(line, &end, 10);
    memoryStatus.size = intValue * pageSize;
    intValue = strtoull(end, &end, 10);
    memoryStatus.resident = intValue * pageSize;
    intValue = strtoull(end, &end, 10);
    memoryStatus.shared = intValue * pageSize;
    intValue = strtoull(end, &end, 10);
    memoryStatus.text = intValue * pageSize;
    intValue = strtoull(end, &end, 10);
    memoryStatus.lib = intValue * pageSize;
    intValue = strtoull(end, &end, 10);
    memoryStatus.data = intValue * pageSize;
    intValue = strtoull(end, &end, 10);
    memoryStatus.dt = intValue * pageSize;
    printf("size=%lu resident= %lu shared=%lu text=%lu data=%lu usedmem=%lu(KB)\r\n",memoryStatus.size,memoryStatus.resident,
	    memoryStatus.shared,memoryStatus.text,memoryStatus.data,memoryStatus.resident - memoryStatus.shared);
}

static size_t processMemoryUsage(){
#if OS(LINUX)
    ProcessMemoryStatus memoryStatus;
    currentProcessMemoryStatus(memoryStatus);
    return (memoryStatus.resident - memoryStatus.shared);
#elif OS(FREEBSD)
    static size_t pageSize = sysconf(_SC_PAGE_SIZE);
    struct kinfo_proc info;
    size_t infolen = sizeof(info);

    int mib[4];
    mib[0] = CTL_KERN;
    mib[1] = KERN_PROC;
    mib[2] = KERN_PROC_PID;
    mib[3] = getpid();

    if (sysctl(mib, 4, &info, &infolen, nullptr, 0))
        return 0;

    return static_cast<size_t>(info.ki_rssize - info.ki_tsize) * pageSize;
#else
#error "Missing a platform specific way of determining the memory usage"
#endif
}

void MemoryPressureHandler::respondToMemoryPressure(bool critical) { 
    uninstall();
    double startTime = WTF::monotonicallyIncreasingTime();//MonotonicTime::now();
    int64_t processMemory = processMemoryUsage();
    releaseMemory(critical);//, synchronous);
    int64_t bytesFreed = processMemory - processMemoryUsage();
    unsigned  holdOffTime = s_maximumHoldOffTime;
    if (bytesFreed > 0 && static_cast<size_t>(bytesFreed) >= s_minimumBytesFreedToUseMinimumHoldOffTime)
        holdOffTime = (WTF::monotonicallyIncreasingTime() - startTime) * s_holdOffMultiplier;
    holdOff(std::max(holdOffTime, s_minimumHoldOffTime));
}

void MemoryPressureHandler::platformReleaseMemory(bool critical) { 
#ifdef __GLIBC__
    malloc_trim(0);
#endif
    ProcessMemoryStatus pms;
    currentProcessMemoryStatus(pms);
}

size_t MemoryPressureHandler::ReliefLogger::platformMemoryUsage(){
    return 0;
}

void MemoryPressureHandler::ReliefLogger::platformLog() { 
    LOG(MemoryPressure,"MemoryPressureHandler.%s",m_logString);
}

}//endof namespace WebCore
#endif//OS(LINUX)
